In the central nervous system (CNS), malignant tumors appear to develop from neural stem cells and tumor stem-like cells. Gliomas, a heterogeneous group of highly invasive brain tumor are resistant to treatment and patients diagnosed with these tumors have a poor prognosis. In large part, the failure of treatments designed to combat gliomas is because these tumors are highly invasive and targeting all sites of tumor formation distant from the parent tumor has proven difficult. We have identified the basic helix-loop-helix (bHLH) DNA binding protein Hand2 as a potential targeted molecule for treatment of glioma. A normal functional partner of Hand2, Twist1, is highly expressed in glioma and has a function in regulating tumor progression and invasiveness. Loss of Twist1 function in glioma causes these tumors to regress and become significantly less invasive suggesting that treatment strategies based on a reduction of Twist1 expression would have a positive outcome. We present evidence that extrinsic signaling molecules that regulate Hand2, BMP4 and Wnt-11, induce Hand2 expression in glioma with a concomitant decrease in Twist1. Based on this exciting finding we propose to: 1) assess the effect of overexpression of Hand2 on Twist1 expression in 8 human-derived glioblastoma cell lines using a heterotopic- to-orthotopic propagation and implantation approach with the expectation that abrogation of Twist1 expression by Hand2 will reduce glioma cell invasiveness, viability and tumorigenicity;2) determine the therapeutic efficacy of Hand2 in vitro using a novel targeting strategy;and 3) test the in vivo efficacy of Hand2 in an orthotopic glioma mouse model. We will take advantage of a novel viral delivery system to comprehensively bring Hand2 to all tumor cells in the CNS, with the goal of improving the therapeutic outcome for patients diagnosed with glioma. PUBLIC HEALTH RELEVANCE: Malignant gliomas constitute the majority of human brain tumors. Despite efforts to improve surgical, radiological and chemotherapeutic treatment strategies, the prognosis for patients with glioma remains poor. A major problem is that glioblastoma cells have a propensity to migrate away from the main tumor mass and invade the surrounding brain tissue. We propose to test a new treatment strategy that might be used to track down the dispersed glioma cells that escape from the primary lesion and transduce them with a regulatory protein that may inhibit their malignant characteristics. The long-term goal of this R21 application is to test the feasibility of a targeted treatment for glioma;we hope to develop our approach to the point where we can develop clinical trials for improved treatment of glioma.